Rev Bras Otorrinolaringol 2007;73(2):239-44.

ORIGINAL ARTICLE

Occupational hearing loss in teachers: a probable diagnosis.

Regina Helena Garcia Martins 1, Elaine Lara Mendes Tavares 2, Arlindo C. Lima Neto 3, Marisa P. Fioravanti 4

Keywords: hearing loss, teacher, noise.

Summary

T

eachers frequently report auditory symptoms and excessive noise in classrooms, but noise level measurements are not done routinely. Study model - a prospective clinical trial. Aim - To study auditory symptoms and audiometric exams of teachers and classroom noise levels. Material and Method: Data from two groups, GI (40 teachers) and GII (40 voluntaries) were studied as follows: age, gender, working conditions, audiometric exams, and classroom noise levels. Results - In GI there were more females (86%), working in basic teaching (75%), in classes with 21-40 students (70%), with workloads between 26 and 40 hours per week (47%), and variable professional teaching time. Most teachers in GI reported excessive classroom noise (93.5%) and auditory symptoms (65%). In GI, 25% of teachers presented audiometric alterations (versus 10% of controls), with an acoustic notch predominating (11.25%; p0.05). All of the participants had a type A normal tympanometric curve. Classroom noise level - maximum and minimum classroom sound pressure level verification values and the Leq are shown on Table 3; significant environmental noise was found at all teaching levels, at around 87.4dB (A), reaching 89dB (A) in junior school.

Figure 2. Results of audiometric exams of teachers (GI).

DISCUSSION

Figure 3. Results of audiometric exams of volunteers (GII).

This study shows that there were more female teachers in the sample group. Many of them had classrooms with many students and worked over 40 hours a week. This workload probably reflects low wages and the need to supplement the family income, as some authors have pointed out.13-14 The working environment of teachers should receive more attention, given the time they remain in classrooms. Crowded classrooms generate significant noise and place excessive demands on phonation. In this context noise verification has not been routine or even required. Most of the teachers in this study reported excessive classroom noise. 190 of 240 teachers assessed by Pérez Fernandez & Preciato López14-15 made similar complaints in a specific questionnaire. Based on our study we believe that teachers exposed to classroom noise may develop occupational hearing loss throughout their career, given the significant number of auditory symptoms, frequent reports of excessive classroom noise, a large number of altered audiometries compared to the control group (40 x 18), and high classroom sound pressure values in teachers belonging to the GI group. Many teachers had notches in their audiometric configuration, reinforcing the abovementioned assumption. This curve is typical of noise-induced hearing loss and

Table 2. Audiometric tracing configuration of teachers (GI) and of the control group (GII) according to the number of ears tested. Sample group

Control group

N

%

N

%

Value dep

Normal test

120

75.00

72

90.00

0.003*

Acoustic drop

18

11.25

1

1.20

0.003*

Sloping

13

8.10

6

7.50

0.43

Tendency to notches

3

1.87

1

1.20

0.36

Inverted U

2

1.25

0

0.00

0.16

Horizontal

2

1.25

0

0.00

0.16

2

1.25

0

0.00

0.16

160

100

80

100

Audiometric tracing

Rising Total

Table 3. Minimum and maximum values and the Leq of classroom noise level verification in different teaching levels (in dBA). Noise level (dBA)*

Leq B(A)

Leq dB(A)

School level

Minimum

Maximum

Minimum

Maximum

Basic School

63.7

87.4

73.5

82.5

Elementary School

59.8

87.4

69.6

84.2

Middle School

66.9

89.0

74.6

86.4

* Leq –equivalent noise level.

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was found in only 1 control group volunteer and in 18 sample group teachers. This diagnosis, however, is based on a reduction of audiometric thresholds when compared to pre-placement exams, which have not been standardized for teachers. Confirmation, therefore, is limited. Verification of classroom sound pressure levels is not done routinely, but our investigation revealed elevated values, ranging from 59.8 dB (A) to 89 dB (A). If the acceptable noise level for industry workers is 85dB, and that studies on acoustics applied to education suggest tolerable classroom sound pressures of 40 to 70dB(A),2,16 we conclude that teachers are exposed to excessive noise levels, notwithstanding Bovo & Galceran`s17 findings of classroom noise levels up to only 55dB. The regulating rule number 15 of the Ordinance 3.214/78,18 which defines tolerance levels for exposure to noise, refers to continuous and intermittent noise, such as that in classrooms. Jiang19 underlines the harmful effects of noise originating outside classrooms, showing an increased prevalence of hypoacusis at high frequencies in physical education teachers. Various authors in past decades have tried to demonstrate the harmful effects of exposure to excessive noise on auditory pathways. This includes studies of industry machine operators,20,21 musicians,22 military personnel,23 drivers,24 and other recently investigated classes such as hospital workers25 and neonates in ICUs.26 These papers have provided the basis for assuring the health promotion rights of various workers. Few of these studies, however, have focused on teachers, who experience inadequate working conditions and frequent auditory symptoms.

(PAIR). In: Lopes Filho O, Campos CAH, editor. Tratado de Otorrinolaringologia. São Paulo: Roca; 1994. p.93449. 2. Suter AH. The handbook of hearing and the effects of noise: physiology, psychology and public health. Ear and Hear 1996;17(2):176-7. 3. Couto HA, Santino E. Audiometrias ocupacionais: Guia prático. Belo Horizonte: Ergo editora; 1995. p. 116. 4. Coles RRA, Lutman ME, Buffin JT. Guideliness on the diagnosis of noise-induced hearing loss for medico legal purposes. Clin Otolaryngol Allied Sci 2000; 25(4):26473. 5. Oliveira CG. Fonoaudiologia preventiva em saúde do trabalhador. In: Marchesan IQ, Zorzi JL, Gomes ICD. (editors). Tópicos em fonoaudiologia. 1ª edição. São Paulo: Lovise; 1996. v.3, p.121-29. 6. Anderson K. The problem of classroom acoustics: the typical classroom soundscape is a barrier to learning. Semin Hear 2004; 25:117-29. 7. Seligman J. Efeitos não auditivos e aspectos psicossociais no indivíduo submetido a ruído intenso. Rev Bras Otorrinolaringol 1993; 59:257-9. 8. Pereira MJ, Santos TMM, Viola IC. Influência do nível de ruído em sala de aula sobre a performance vocal do professor. In: Ferreira LP, Costa HO. (eds.) Voz Ativa - Falando sobre o profissional da voz. 1ª edição. São Paulo: Roca; 2000. p.57-65. 9. American college of occupational medicine noise and hearing conservation committee. Occupational noise - induced hearing loss. J Occup Med 1989;31:996. 10.Brasil - portaria nº 19, de 09 de abril de 1998 - diretrizes e parâmetros mínimos para avaliação e acompanhamento da audição em trabalhadores expostos a níveis de pressão sonora elevados. Ministério do trabalho. Secretaria de segurança do trabalho. Diário Oficial da União, Brasília, 22 de abril de 1998. 11.Comitê nacional de ruído e conservação auditiva. Perda induzida pelo ruído relacionada ao trabalho. Acta AWHO 1994; 13:126-7. 12.Russo ICP, Santos TMM. A prática da audiologia clínica. 4ª. Ed S. Paulo: Cortez; 1993. pág. 253. 13.Fuess VLR, Lorenz, MC. Disfonia em professores do ensino municipal: prevalência e fatores de risco. Rev Bras Otorrinolaringol 2003;69(6):807-12. 14.Preciado JA, Garcia Tapia RE, Infante JC. Estudio de la prevalencia de los trastornos de la voz en los profesionales de la enseñanza. Factores que intervienen en su aparición o en su mantenimiento. Acta Otorrinolaringol Esp 1998;49(2):137-42. 15.Pérez Fernandez CA. & Preciado López J. Nódulos de cuerdas vocales. Factores de riesgo en los docentes. Estudo de casos y controles. Acta Otorrinolaringol Esp 2003;54:253-60. 16.Brasil - Associação Brasileira de Normas Técnicas, ABNT; norma NBR 10152. Níveis de ruído para conforto acústico (nb95). 1990. 17.Bovo R, Galceran M. Le disfonie disfunzionali como patologia professionale. In: Fórum Europeo de Ciência, Seguridad y Salud 3. 1998, Oviedo. Ponencia. Oviedo, 1998. 18.Brasil Norma Regulamentadora de nº 15 (NR-15) da Portaria 3.214/78 do Ministério do Trabalho e Emprego - Secretaria de Segurança e Saúde no Trabalho - Atividades e Operações Insalubres - Diário Oficial da União, Brasília, 08 de junho de 1978.

CONCLUSION The high frequency of auditory symptoms, constant reports of excessive classroom noise, the detection of a significant percentage of altered exams with a predominance of notches, and verification of high environmental noise levels, suggest that occupational hearing loss due to noise exposure is present in teachers. This diagnosis needs to be confirmed through pre-placement and periodic exams and further careful studies similar to this paper. REFERENCES 1. Alberti PW. Deficiência auditiva induzida pelo ruído

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19.Jiang T. Risks of noise-induced hearing loss for physical education teachers. J Occup Environ Med 1997;39(10):925-6. 20.Prince MM, Gilbert SJ, Smith RJ, Stayner LT. Evaluation of the risk of noise-induced hearing loss among unscreened male industrial workers. J Acoust Soc Am 2003;113(2):871-80. 21.Harger MR, Barbosa-Branco A. Effects on hearing due to the occupational noise exposure of marble industry workers in the Federal District, Brazil. Rev Assoc Med Bras 2004;50(4):396-9. 22.Juman S, Karmody CS, Simeon D. Hearing loss in steelband musicians. Otolaryngol Head Neck Surg 2004;131(4):461-5.

23.Sewell RK, Song C, Bauman NM, Smith RJ, Blanck P. Hearing loss in union army veterans from 1862 to 1920. Laryngoscope 2004;114(12):2147-53. 24.Correa Filho HR, Costa LS, Hoehne EL, Perez MA, Nascimento LC, de Moura EC. Noise-induced hearing loss and high blood pressure among city bus drivers. Rev Saude Pública 2002;36(6):693-701. 25.Giovinetto R, Roletti S, Saporiti F. The percentage of the population exposed to harmful acoustic pollution levels resulting from vehicular traffic in the hospital area of turin. Radiat Prot Dosimetry 2004;111(4):385-9. 26.Kent WD, Tan AK, Clarke MC, Bardell T. Excessive noise levels in the neonatal ICU: potential effects on auditory system development. J Otolaryngol 2002;31(6):35560.

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